摘要：
Background背景Problems that process input and generate a simple "yes" or "no" answer are called decision problems. One class of decision problems, the NP-complete problems, are not amenable to general e... 阅读全文
摘要：
概念全排列的生成算法有很多种，有递归遍例，也有循环移位法等等。C++/STL中定义的next_permutation和prev_permutation函数则是非常灵活且高效的一种方法，它被广泛的应用于为指定序列生成不同的排列。本文将详细的介绍prev_permutation函数的内部算法。按照STL... 阅读全文
摘要：
Time limit: 3.000 seconds限时：3.000秒Background背景Order is an important concept in mathematics and in computer science. For example, Zorn's Lemma states: "a partially ordered set in which every chain has ... 阅读全文